Experimental and Numerical Investigation into the Quasi-Static Crushing Behaviour of the S-Shape Square Tubes

2011 ◽  
Vol 27 (4) ◽  
pp. 585-596 ◽  
Author(s):  
A. Khalkhali ◽  
A. Masoumi ◽  
A. Darvizeh ◽  
M. Jafari ◽  
A. Shiri
Keyword(s):  
Numerical Investigation ◽  
Parametric Study ◽  
Experimental Tests ◽  
Deformation Mode ◽  
Numerical Approach ◽  
Vehicle Body ◽  
Design Parameters ◽  
Radius Of Curvature ◽  
Element Analysis ◽  
Static Tests

ABSTRACTVehicle energy absorbing components usually have a curved shape to avoid interference with other components like engine, driving system and fuel tank, etc. Crush behaviour of the S-shape square tubes, as a simplified model of front member of a vehicle body, is investigated in the present study. Experimental and numerical investigation into the quasi static crushing of such tubes was performed. Experimental tests were carried out with cross head speed of 5mm/min. Finite element analysis was performed using ABAQUS/Explicit to simulate quasi-static tests conditions. The predicted crushing characteristics such as global deformation mode, plastic folding mode and load-displacement response obtained by numerical approach were found to be in good agreement with the experimental results. The validated numerical model was then used in the parametric study to examine the effect of design parameters such as wall thickness, web width, curve angle and radius of curvature on the energy absorption capability of the S-shape square tubes. It is shown that some interesting relationships can be discovered by the parametric study to be used as useful design approach for improving the performance of the S-shape tubes.

Experimental Analysis of Self-Folding SMA-Based Sheet Design for Simulation Validation

2014 ◽  
Author(s):  
Aaron C. Powledge ◽  
Darren J. Hartl ◽  
Richard J. Malak
Keyword(s):  
Performance Metrics ◽  
Permanent Deformation ◽  
Material Behavior ◽  
Image Correlation ◽  
Design Parameters ◽  
Radius Of Curvature ◽  
Element Analysis ◽  
Performance Metric ◽  
3D Digital Image Correlation ◽  
Thermally Actuated

The goal of this research is to experimentally characterize the capabilities of a concept for a self-folding reconfigurable sheet for use in origami-inspired engineering design and to use this characterization to validate simulations of physics-based models of the sheet. The sheet consists of an active, self-morphing laminate that contains two shape memory alloy (SMA) mesh layers and a passive compliant medium between these layers. The SMA layers are thermally actuated, allowing bending to occur in both positive and negative directions to create soft hill and valley folds. These folds are completely reversible, allowing the structure to fold and unfold without permanent deformation. Unlike past work on self-folding structures, these sheets can have folds along any line, be subsequently unfolded, and then be folded again in a new way. To explore the effect of changing design parameters on the performance metrics of the sheet, it is desirable to use Finite Element Analysis (FEA) simulations instead of relying on time consuming experiments. Such models have been created incorporating user material subroutines (UMATs) in an FEA solver such as Abaqus to capture material behavior, but these must now be validated against experimental data to establish how well they match experimental performance. The primary performance metric of the sheet was chosen to be the radius of curvature measured perpendicularly to the line of heating. Both experiment and simulation focus on the radius of curvature achieved by the sheet for a given set of design parameters and actuation path. The goal of validation is to achieve a desirable level of agreement and repeatability in these results. To measure the deformation and curvature in the sheet as it actuates, a 3D Digital Image Correlation (3D DIC) system is employed to track the movement of points along the surface of the sample as it is heated to a temperature above the transformation temperature of the SMA and allowed to fully actuate. These tools are utilized for a number of samples so that validation of the sheet encompasses multiple values for each of the primary design parameters.

Application of Experimental and Finite Element Methods to Analyse the Effect of Inner Diaphragms of Automotive T-Frame

2005 ◽  
Author(s):  
CheeFai Tan ◽  
Mohd Hazani Hj Shafie ◽  
Shamsul Anuar Shamsudin ◽  
Md. Radzai Said
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Experimental Tests ◽  
Vehicle Body ◽  
Element Analysis ◽  
Automotive Body ◽  
Passenger Safety ◽  
Specific Loading ◽  
Joint Rigidity ◽  
External Forces

The framework of the automotive body structure is comprised of thin walled section members in the form of overlapping sheet metals fastened by spot-welds. In analysing the structure of the vehicle body, it is assumed that the intersecting angles at which the members are joined together varies according to the external forces. These frame joints are subject to dynamic and static loads. Experiments and finite element analysis can determine joint rigidity. The effective design of the vehicle T-joint can maximise passenger safety and reduce the vehicle weight. Thus, these were conducted to investigate the deflection of the vehicle T-frame. This paper discuss the behaviour of the T-frame under a specific loading. In addition, a series of T-frame with inner diaphragms (baffles) at various locations in the sill member were designed in order to investigate the effect of the inner diaphragms and non-continuous closed hat section in the sill member. The results from the experimental tests were compared with the results of the finite element analysis. We demonstrated the effectiveness of the inner diaphragm in the automotive T-frame.

scholarly journals Modeling Bioinspired Fish Scale Designs via a Geometric and Numerical Approach

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5378
Author(s):  
Ailin Chen ◽  
Komal Thind ◽  
Kahraman G. Demir ◽  
Grace X. Gu
Keyword(s):  
Transition Point ◽  
Geometric Analysis ◽  
Numerical Approach ◽  
Shear Loading ◽  
Design Parameters ◽  
Fish Scale ◽  
Fish Scales ◽  
Element Analysis ◽  
Puncture Resistance ◽  
Complex Interactions

Fish scales serve as a natural dermal armor with remarkable flexibility and puncture resistance. Through studying fish scales, researchers can replicate these properties and tune them by adjusting their design parameters to create biomimetic scales. Overlapping scales, as seen in elasmoid scales, can lead to complex interactions between each scale. These interactions are able to maintain the stiffness of the fish’s structure with improved flexibility. Hence, it is important to understand these interactions in order to design biomimetic fish scales. Modeling the flexibility of fish scales, when subject to shear loading across a substrate, requires accounting for nonlinear relations. Current studies focus on characterizing these kinematic linear and nonlinear regions but fall short in modeling the kinematic phase shift. Here, we propose an approach that will predict when the linear-to-nonlinear transition will occur, allowing for more control of the overall behavior of the fish scale structure. Using a geometric analysis of the interacting scales, we can model the flexibility at the transition point where the scales start to engage in a nonlinear manner. The validity of these geometric predictions is investigated through finite element analysis. This investigation will allow for efficient optimization of scale-like designs and can be applied to various applications.

Effects of Stent Design Parameters on Normal Artery Wall Mechanics

2006 ◽  
Vol 128 (5) ◽  
pp. 757-765 ◽  
Author(s):  
Julian Bedoya ◽  
Clark A. Meyer ◽  
Lucas H. Timmins ◽  
Michael R. Moreno ◽  
James E. Moore
Keyword(s):  
Radial Displacement ◽  
Design Parameters ◽  
Radius Of Curvature ◽  
Stent Design ◽  
Artery Wall ◽  
Element Analysis ◽  
Radial Strength ◽  
Stent Strut ◽  
Invasive Techniques ◽  
Normal Artery

A stent is a device designed to restore flow through constricted arteries. These tubular scaffold devices are delivered to the afflicted region and deployed using minimally invasive techniques. Stents must have sufficient radial strength to prop the diseased artery open. The presence of a stent can subject the artery to abnormally high stresses that can trigger adverse biologic responses culminating in restenosis. The primary aim of this investigation was to investigate the effects of varying stent “design parameters” on the stress field induced in the normal artery wall and the radial displacement achieved by the stent. The generic stent models were designed to represent a sample of the attributes incorporated in present commercially available stents. Each stent was deployed in a homogeneous, nonlinear hyperelastic artery model and evaluated using commercially available finite element analysis software. Of the designs investigated herein, those employing large axial strut spacing, blunted corners, and higher amplitudes in the ring segments induced high circumferential stresses over smaller areas of the artery’s inner surface than all other configurations. Axial strut spacing was the dominant parameter in this study, i.e., all designs employing a small stent strut spacing induced higher stresses over larger areas than designs employing the large strut spacing. Increasing either radius of curvature or strut amplitude generally resulted in smaller areas exposed to high stresses. At larger strut spacing, sensitivity to radius of curvature was increased in comparison to the small strut spacing. With the larger strut spacing designs, the effects of varying amplitude could be offset by varying the radius of curvature and vice versa. The range of minimum radial displacements from the unstented diastolic radius observed among all designs was less than 90μm. Evidence presented herein suggests that stent designs incorporating large axial strut spacing, blunted corners at bends, and higher amplitudes exposed smaller regions of the artery to high stresses, while maintaining a radial displacement that should be sufficient to restore adequate flow.

Simulation of Secondary Contact to Generate Very High Accelerations

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Stuart T. Douglas ◽  
Moustafa Al-Bassyiouni ◽  
Abhijit Dasgupta ◽  
Kevin Gilman ◽  
Aaron Brown
Keyword(s):  
Finite Element ◽  
Contact Stiffness ◽  
Experimental Tests ◽  
Element Model ◽  
Parametric Modeling ◽  
Design Parameters ◽  
Secondary Contact ◽  
Element Analysis ◽  
Secondary Impact ◽  
Very High

This paper investigates the design of a typical commercially available drop system for generating very high shock and drop accelerations. Some commercially available drop towers produce accelerations greater than 5000 G by utilizing the dynamics of secondary impact, using an attachment termed a dual mass shock amplifier (DMSA). Depending on the design, some DMSAs are capable of repeatedly generating accelerations as high as 100,000 G. The results show that a finite element model (FEM) can capture the peak acceleration for the drop tower and the DMSA within 15%. In this paper, a detailed description of the test equipment and modeling techniques is provided. The effects of different design parameters, such as table mass, spring stiffness, and programmer material properties, on the drop profile, are investigated through parametric modeling. The effects of contact parameters on model accuracy are explored, including constraint enforcement algorithms, contact stiffness, and contact damping. Simple closed-form analytic models are developed, based on the basic principles of a single impact and the dynamics of secondary impact. Model predictions are compared with test results. Details of the test methodology and simulations guidelines are provided. Detailed finite element analysis (FEA) is conducted and validated against the experimental tests and compared to the simplified theoretical simulations. Benefits in exploring FEM to simulate contact between materials can be extrapolated to different architectures and materials such that with minimal experimental validation impact acceleration can be determined.

A Simplified Design Model for Modular Steel Buildings Subject to Vapor Cloud Explosions (VCEs)

2020 ◽  
Vol 14 ◽  
Author(s):  
Osama Bedair
Keyword(s):  
Dynamic Response ◽  
Minimum Cost ◽  
Design Parameters ◽  
Front Wall ◽  
Steel Buildings ◽  
Element Analysis ◽  
Analysis And Design ◽  
Vapor Cloud ◽  
Building Components ◽  
Analytical Expressions

Background: Modular steel buildings (MSB) are extensively used in petrochemical plants and refineries. Limited guidelines are available in the industry for analysis and design of (MSB) subject to accidental vapor cloud explosions (VCEs). Objectives: The paper presents simplified engineering model for modular steel buildings (MSB) subject to accidental vapor cloud explosions (VCEs) that are extensively used in petrochemical plants and refineries. Method: A Single degree of freedom (SDOF) dynamic model is utilized to simulate the dynamic response of primary building components. Analytical expressions are then provided to compute the dynamic load factors (DLF) for critical building elements. Recommended foundation systems are also proposed to install the modular building with minimum cost. Results: Numerical results are presented to illustrate the dynamic response of (MSB) subject to blast loading. It is shown that (DLF)=1.6 is attained at (td/t)=0.4 for front wall (W1) with (td/T)=1.25. For side walls (DLF)=1.41 and is attained at (td/t)=0.6. Conclusions: The paper presented simplified tools for analysis and design of (MSB) subject accidental vapor cloud blast explosions (VCEs). The analytical expressions can be utilized by practitioners to compute the (MSB) response and identify the design parameters. They are simple to use compared to Finite Element Analysis.

Static and dynamic response of sandwich beams with lattice and pantographic cores

2021 ◽  
pp. 109963622110338
Author(s):  
Yury Solyaev ◽  
Arseniy Babaytsev ◽  
Anastasia Ustenko ◽  
Andrey Ripetskiy ◽  
Alexander Volkov
Keyword(s):  
Mechanical Performance ◽  
Lattice Structure ◽  
Unit Length ◽  
Experimental Tests ◽  
Plane Geometry ◽  
Sandwich Beams ◽  
Static Tests ◽  
Three Point Bending ◽  
The Core ◽  
The Impact

Mechanical performance of 3d-printed polyamide sandwich beams with different type of the lattice cores is investigated. Four variants of the beams are considered, which differ in the type of connections between the elements in the lattice structure of the core. We consider the pantographic-type lattices formed by the two families of inclined beams placed with small offset and connected by stiff joints (variant 1), by hinges (variant 2) and made without joints (variant 3). The fourth type of the core has the standard plane geometry formed by the intersected beams lying in the same plane (variant 4). Experimental tests were performed for the localized indentation loading according to the three-point bending scheme with small span-to-thickness ratio. From the experiments we found that the plane geometry of variant 4 has the highest rigidity and the highest load bearing capacity in the static tests. However, other three variants of the pantographic-type cores (1–3) demonstrate the better performance under the impact loading. The impact strength of such structures are in 3.5–5 times higher than those one of variant 4 with almost the same mass per unit length. This result is validated by using numerical simulations and explained by the decrease of the stress concentration and the stress state triaxiality and also by the delocalization effects that arise in the pantographic-type cores.

scholarly journals AC Current Ripple in Three-Phase Four-Leg PWM Converters with Neutral Line Inductor

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1430
Author(s):  
Aleksandr Viatkin ◽  
Riccardo Mandrioli ◽  
Manel Hammami ◽  
Mattia Ricco ◽  
Gabriele Grandi
Keyword(s):  
Numerical Simulations ◽  
Pulse Width Modulation ◽  
Neutral Line ◽  
Experimental Tests ◽  
Performance Comparison ◽  
Design Parameters ◽  
Switching Frequency ◽  
Three Phase ◽  
Ac Current ◽  
Current Ripple

This paper presents a comprehensive study of peak-to-peak and root-mean-square (RMS) values of AC current ripples with balanced and unbalanced fundamental currents in a generic case of three-phase four-leg converters with uncoupled AC interface inductors present in all three phases and in neutral. The AC current ripple characteristics were determined for both phase and neutral currents, considering the sinusoidal pulse-width modulation (SPWM) method. The derived expressions are simple, effective, and ready for accurate AC current ripple calculations in three- or four-leg converters. This is particularly handy in the converter design process, since there is no need for heavy numerical simulations to determine an optimal set of design parameters, such as switching frequency and line inductances, based on the grid code or load restrictions in terms of AC current ripple. Particular attention has been paid to the performance comparison between the conventional three-phase three-leg converter and its four-leg counterpart, with distinct line inductance values in the neutral wire. In addition to that, a design example was performed to demonstrate the power of the derived equations. Numerical simulations and extensive experimental tests were thoroughly verified the analytical developments.

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